A. Field of the Invention
The present invention is directed to a unit dose composition for inducing cardiac angiogenesis in a human comprising an therapeutically effective amount FGF-2 or an angiogenically active fragment or mutein thereof. The present invention is also directed to a method for administering a single unit dose composition to a human to induce cardiac angiogenesis while minimizing systemic risk to the patient. The present invention is useful because the disclosed unit dose composition, and method for its administration, provide an alternative to angioplasty or surgical intervention for the treatment of coronary artery disease (CAD) and further provide an adjunct for reducing post myocardial infarct (MI) injury in humans.
B. Background of the Invention
The fibroblast growth factors (FGF) are a family of at least eighteen structurally related polypeptides (named FGF-1 to FGF-18) that are characterized by a high degree of affinity for proteoglycans, such as heparin. The various FGF molecules range in size from 15-23 kD, and exhibit a broad range of biological activities in normal and malignant conditions including nerve cell adhesion and differentiation [Schubert et al., J. Cell Biol. 104:635-643 (1987)]; wound healing [U.S. Pat. No. 5,439,818 (Fiddes)]; as mitogens toward many mesodermal and ectodermal cell types, as trophic factors, as differentiation inducing or inhibiting factors [Clements, et al., Oncogene 8:1311-1316 (1993)]; and as an angiogenic factor [Harada, J. Clin. Invest., 94:623-630 (1994)]. Thus, the FGF family is a family of pluripotent growth factors that stimulate to varying extents fibroblasts, smooth muscle cells, epithelial cells and neuronal cells.
When FGF is released by normal tissues, such as in fetal development or wound healing, it is subject to temporal and spatial controls. However, many of the members of the FGF family are also oncogenes. Thus, in the absence of temporal and spatial controls, they have the potential to stimulate tumor growth by providing angiogenesis.
Coronary artery disease is a progressive condition in humans wherein one or more coronary arteries gradually become occluded through the buildup of plaque (atherosclerosis). The coronary arteries of patients having this disease are often treated by balloon angioplasty or the insertion of stents to prop open the partially occluded arteries. Ultimately, many of these patients are required to undergo coronary artery bypass surgery at great expense and risk. It would be desirable to provide such patients with a medicament that would enhance coronary blood flow so as to reduce the need to undergo bypass surgery.
An even more critical situation arises in humans when a patient suffers a myocardial infarction, wherein one or more coronary arteries or arterioles becomes completely occluded, such as by a clot. There is an immediate need to regain circulation to the portion of the myocardium served by the occluded artery or arteriole. If the lost coronary circulation is restored within hours of the onset of the infarction, much of the damage to the myocardium that is downstream from the occlusion can be prevented. The clot-dissolving drugs, such as tissue plasminogen activator (tPA), streptokinase, and urokinase, have been proven to be useful in this instance. However, as an adjunct to the clot dissolving drugs, it would also be desirable to also obtain collateral circulation to the damaged or occluded myocardium by angiogenesis.
Accordingly, it is an object of the present invention to provide a medicament and a mode of administration that provides human patients with cardiac angiogenesis during coronary artery disease and/or post acute myocardial infarction. More particularly, it is a further object of the present invention to provide a therapeutic dose of an FGF and a mode of administration to humans that provide the desired property of cardiac angiogenesis, while minimizing adverse effects.
Many of the various FGF molecules have been isolated and administered to various animal models of myocardial ischemia with varying and often times opposite results. According to Battler et al., xe2x80x9cthe canine model of myocardial ischemia has been criticized because of the abundance of naturally occurring collateral circulation, as opposed to the porcine model, which xe2x80x98excelsxe2x80x99 in its relative paucity of natural collateral circulation and its resemblance to the human coronary circulation.xe2x80x9d Battler et al., xe2x80x9cIntracoronary Injection of Basic Fibroblast Growth Factor Enhances Angiogenesis in Infarcted Swine Myocardium, xe2x80x9d JACC, 22(7): 2001-6 (December 1993) at page 2002, col.1. However, Battler et al., who administered bovine bFGF (i.e., FGF-2) to pigs in a myocardial infarct model, considered the varying results that are obtained from one animal species to another, and expressly discloses that the divergent results xe2x80x9cthus emphasiz[e] the caution that must be exercised in extrapolating results from different animal models.xe2x80x9d Battler et al., at page 2005, col.1. Further, Battler points out that xe2x80x9cthe dosage and mode of administration of bFGF [i.e., bovine FGF-2] may have profound implications for the biologic effect achieved.xe2x80x9d Battler, et al., at page 2005, col.1. Thus, it is a further object of this invention to discover a dosage and a mode of administration of a fibroblast growth factor that would provide for the safe and efficacious treatment of CAD and/or post MI injury in a human patient. More generally, it is an object of the present invention to provide a pharmaceutical composition and method for inducing angiogenesis in a human heart.
The Applicants have discovered that administering a single unit dose of about 0.2 xcexcg/kg to about 48 xcexcg/kg of rFGF-2 or an angiogenically active fragment or mutein thereof into one or more coronary vessels (IC) or a peripheral vein (IV) of a human patient in need of coronary angiogenesis, unexpectedly provided the human patient with a rapid and therapeutic coronary angiogenesis that resulted in an unexpectedly large increase (i.e., 96 and 100 seconds of increase in the mean change from baseline for all groups at 2 and 6 months) in the treated patient""s exercise tolerance time (ETT) that persisted for an unexpectedly long duration (i.e., 6 months as of this writing). These changes should result in a decreased need for standard revascularization procedures. By the term xe2x80x9ccoronary angiogenesis,xe2x80x9d as used herein, is meant the formation of new blood vessels, ranging in size from capillaries to arterioles which act as collaterals in coronary circulation. By way of comparison, angioplasty is considered a therapeutic success if it provides an increase in a patient""s ETT of greater than 30 seconds compared to the placebo.
Accordingly, in one aspect, the invention is directed to a unit dose of rFGF-2 comprising a safe and therapeutically effective amount of rFGF-2 or an angiogenically active fragment or mutein thereof. Typically, the safe and therapeutically effective amount comprises about 0.2 xcexcg/kg to about 48 xcexcg/kg of rFGF-2 or an angiogenically active fragment or mutein thereof, based upon ideal body weight. In other embodiments, the safe and therapeutically effective amount of the unit dose comprises 0.2 xcexcg/kg to 2.0 xcexcg/kg, greater than 2.0 xcexcg/kg to less than 24 xcexcg/kg, or 24 xcexcg/kg to 48 xcexcg/kg IC of rFGF-2 or an angiogenically active fragment or mutein thereof. In another embodiment, the safe and therapeutically effective amount of the unit dose comprises 18 xcexcg/kg to 36 xcexcg/kg IV of rFGF-2 or an angiogenically active fragment or mutein thereof. Expressed in absolute terms, the unit dose of the present invention comprises 0.008 mg to 7.2 mg, more typically 0.3 mg to 3.5 mg, of FGF-2 or an angiogenically active fragment or mutein thereof. A suitable FGF-2 is the rFGF-2 of SEQ ID NO: 2 or an angiogenically active fragment or mutein thereof.
In another aspect, the present invention is directed to a method of treating a human patient for CAD or to induce coronary angiogenesis therein. The method comprises administering into one or more coronary vessels or a peripheral vein of a human patient in need of treatment for coronary artery disease (or in need of angiogenesis) a safe and therapeutically effective amount of a recombinant FGF-2 (rFGF-2) or an angiogenically active fragment or mutein thereof. Typically, a portion of the safe and therapeutically effective amount is administered to each of two coronary vessels. The safe and therapeutically effective amount comprises about 0.2 xcexcg/kg to about 48 xcexcg/kg, of rFGF-2 or an angiogenically active fragment or mutein thereof in a pharmaceutically acceptable carrier. In other embodiments, the safe and therapeutically effective amount comprises 0.2 xcexcg/kg to 2 xcexcg/kg,  greater than 2 xcexcg/kg to  less than 24 xcexcg/kg, or 24 xcexcg/kg to 48 xcexcg/kg of rFGF-2 an angiogenically active fragment or mutein thereof in a pharmaceutically acceptable carrier. In absolute terms, the amount of rFGF-2 or angiogenically active fragment or mutein thereof that is used in the above method comprises 0.008 mg to 7.2 mg, more typically 0.3 mg to 3.5 mg, of rFGF-2 or an angiogenically active fragment or mutein thereof.
Because FGF-2 is a glycosoaminoglycan (e.g., heparin) binding protein and the presence of a glycosoaminoglycan optimizes activity and AUC (see FIGS. 3 and 4), the IC dosages of RFGF-2 of the present invention typically are administered from 0-30 minutes prior to the administration of a glycosoaminoglycan, such as a heparin. The heparin is administered IC or IV, typically IV. Optionally, the heparin is combined with the unit dose composition.
Because rFGF-2 releases nitric oxide which is a potent vasodilator, aggressive fluid management prior to (proactively) and during the infusion is critical to patient""s safety. Administration of IV fluids (e.g., 500-1000 mL of normal saline) to establish a wedge pressure of 12 mm Hg prior to infusion and administration of boluses of IV fluids (e.g., 200 mL normal saline) for decreases of systolic blood pressure (e.g.,  less than 90 mm Hg) associated with infusion optimized the safety of administration of rFGF-2 by IC or IV infusion to human patients.
Because EDTA is a potent chelator of calcium which is required for normal myocardial contraction and cardiac conduction, minimizing the concentration of EDTA is critical to patient""s safety. A concentration of EDTA less than 100 xcexcg/ml in the unit dose composition optimized the safety of administration of rFGF-2 by IC or IV infusion to human patients.
Because a sudden bolus of rFGF-2 is associated with profound hypotension in animals, the rate of infusion is critical to patient""s safety. Administration at 0.5 to 2 mL per minute, typically 1 mL per minute, optimized the safety of administration of rFGF-2 by IC or IV infusion to human patients.
The unexpected magnitude and duration of the therapeutic benefit that was provided to human patients in need of coronary angiogenesis by the unit dose composition and method of administration was seen as early as two weeks after the single unit dose was administered, and persisted for 6 months after the single unit dose was administered IC or IV, as determined by measuring art-recognized clinical endpoints such as ETT, the xe2x80x9cSeattle Angina Questionnairexe2x80x9d (SAQ) and MRI of the target areas of the heart. In particular, when the ETT of 58 human CAD patients was assessed by treadmill at baseline, and at 1 month, 2 months, and 6 months after administration of a single unit dose of rFGF-2 by IC or IV routes, clinical benefit was observed in some patients in all dosage groups. See Table 1. Increases in exercise capacity appear between 1 and 2 months. The mean ETT increased to greater than 60 seconds at 2 and 6 months with greater benefit being seen in the higher dose group (24-48 xcexcg/kg) than in the mid (6-12 xcexcg/kg) or low (0.33-2.0 xcexcg/kg) dose groups. (See Table 1.) Particularly unexpected and unpredicted by animal models, were the mean increases in ETT in human patients of 93.4 and 87.5 seconds that were observed at 2 and 6 months, respectively, post-dosing for those patients administered a unit dose of rFGF-2 by IV. Even assuming a placebo effect, the mean change from baseline for the ETT seconds still allowed an unexpectedly favorable comparison of results with angioplasty.
When the quality of life of 48 human CAD patients were assessed by a validated, disease specific questionnaire, the Seattle Angina Questionnaire (SAQ), at baseline (i.e., prior to dosing), and at 2 and 6 months after a single receiving a single unit dose of rFGF-2 of the present invention by IC or IV routes, the mean change from baseline for the 5 scales measured by the SAQ increased in a clinically significant manner for all dosage ranges whether administered IC or IV. (Tables 2-6). In particular, the five scales assessed by the SAQ are exertional capacity, angina stability, angina frequency, treatment satisfaction, and disease perception. Relative to the baseline, the mean score for exertional capacity increased by 10.9 to 20.2 at 2 months; and by 16.5 to 24.1 at 6 months. For angina stability, the mean score increased by 32.1 to 46.2 at 2 months; and by 16.7 to 23.2 at 6 months. For angina frequency, the mean score increased by 20.0 to 32.9 at 2 months; and by 11.4 to 36.7 at 6 months. For treatment satisfaction, the mean score increased by 8.5 to 19.8 at 2 months; and by 6.3 to 19.8 at 6 months. For disease perception, the mean score increased by 20.2 to 27.8 at 2 months; and by 23.8 to 34.0 at 6 months. Generally, a change of 8 points on any scale is considered clinically significant. Thus, the observed changes of 8.5-46.2 are clinically significant for each of the five scales that were assessed. Even assuming a placebo effect whereby a mean change from baseline of 14 points is considered clinically significant, the results still provide for an unexpectedly superior effect at almost all scales that were assessed.
As part of this study, MRI was also performed on 33 human patients diagnosed with CAD to assess the effect of administering a single unit dose of rFGF-2 on their cardiac ejection fraction, regional myocardial function and perfusion (delayed arrival zone). Specifically, the patients were administered a single unit dose of 0.33 xcexcg/kg to 48 xcexcg/kg IC or 18 xcexcg/kg to 36 xcexcg/kg IV of rFGF-2 of SEQ ID NO: 2. When the 33 human CAD patients were assessed by resting cardiac magnetic resonance imaging (MRI) at baseline (i.e., prior to treatment), and 1, 2 and 6 months after treatment with a single unit dose of rFGF-2 of the invention by IC or IV routes, the patients exhibited a highly statistically significant response to the method of treatment as objectively measured by increased target wall thickening, target wall motion, and target area collateral extent, and by decreased target area delayed arrival extent. (Table 7) By way of summary, at 1, 2 and 6 months, the target wall thickening increased relative to baseline at 4.4%, 6.3% and 7.7%, respectively; the target wall motion increased relative to baseline at 2.7%, 4.4% and 6.4%, respectively; the target area collateral extent increased relative to baseline at 8.3%, 10.9% and 11.2%, respectively; and the target area delayed arrival extent decreased relative to baseline at xe2x88x9210.0%, xe2x88x928.3% and xe2x88x9210.0%, respectively.
The above data demonstrates the clinical efficacy in humans of the present unit dose composition of rFGF-2 or an angiogenically active fragment thereof when administered IC or IV in accordance with the present invention.